What are the main types of wood?

Wood is grouped into hardwoods, softwoods and manufactured boards. Hardwoods come from broad-leaved trees (such as oak and mahogany) and are usually strong, hard and slow-growing. Softwoods come from cone-bearing trees (such as pine) and are cheaper, lighter and faster-growing. Manufactured boards (such as plywood and MDF) are made from wood pieces or fibres glued together, giving large, flat, stable sheets with no natural grain weakness.

What is the difference between ferrous and non-ferrous metals?

Ferrous metals contain iron and, except for stainless steel, will rust if not protected; examples are mild steel and cast iron, and most are magnetic. Non-ferrous metals contain no iron, so they do not rust in the same way; examples are aluminium, copper and brass, and they are often lighter or better at resisting corrosion. An alloy is a mixture of metals (or a metal with another element) made to improve properties, such as brass or stainless steel.

What is the difference between a thermoplastic and a thermosetting plastic?

A thermoplastic softens when heated and can be reshaped many times, which also makes it easy to recycle; examples are acrylic, polythene and PVC. A thermosetting plastic sets hard permanently when first heated and cannot be re-softened or reshaped, so it resists heat well; examples are urea formaldehyde and epoxy resin. The simple test: thermoplastics can be remoulded, thermosets cannot.

How do you choose the right material for a product?

Match the material's properties to the requirements in the specification. List what the product must do (be strong, light, waterproof, look good, survive outdoors) and pick the material whose properties best fit, while weighing cost, availability and environmental impact. A good answer justifies the choice, for example 'aluminium because it is light and resists corrosion outdoors', rather than just naming a material.

Why do a material's properties decide its uses?

A material is chosen because its properties suit the job. A chopping board uses a tough, hygienic hardwood or plastic; an outdoor frame uses corrosion-resistant aluminium; a clear cover uses transparent acrylic. If the properties do not match the need, the product fails: a material that rusts outdoors, or a plastic that melts near heat, would be the wrong choice however cheap it is.

SingaporeDesign and Technology

Materials and their Properties: how N(A)-Level Design and Technology students classify woods, metals and plastics, describe their properties, and choose the right material for a product

A Singapore N(A)-Level Design and Technology (SEAB 7055) module overview of materials. Classifying woods (hardwoods, softwoods, manufactured boards), metals (ferrous, non-ferrous, alloys) and plastics (thermoplastics, thermosets), their key properties and uses, and how to choose the right material by matching properties to the specification, with links to every dot point.

Generated by Claude Opus 4.86 min readSEAB-7055Updated 2026-06-13

Reviewed by: AI editorial process; not yet individually human-reviewed

Jump to a section

What this module covers
Woods
Metals
Plastics
Choosing the right material
How this module is examined
Check your knowledge

What this module covers

Materials and their Properties is the knowledge base for every made product. An N(A)-Level Design and Technology (SEAB 7055) student must classify the three families of material, woods, metals and plastics, describe their key properties, and use that knowledge to choose the right material for a job. This module has four dot points: choosing the right material, and one each on woods, metals and plastics. The recurring exam skill is linking a property to a use, and justifying a material choice against the specification rather than simply naming a material.

See the full set of dot points for this module under /sg-n-level/design-and-technology/syllabus/materials-and-their-properties.

Woods

The woods and their properties dot point classifies wood into hardwoods (strong, from broad-leaved trees), softwoods (cheaper and lighter, from cone-bearing trees) and manufactured boards (plywood, MDF and others, made by gluing wood together for large, stable sheets). It links properties such as strength, grain and workability to typical uses.

Metals

Metals and their properties covers ferrous metals (containing iron, prone to rust), non-ferrous metals (no iron, often lighter or corrosion-resistant) and alloys (mixtures made to improve properties). Key properties include strength, hardness, ductility and corrosion resistance, each pointing to suitable uses.

Plastics

Plastics and their properties divides plastics into thermoplastics (softened and reshaped many times, easy to recycle) and thermosetting plastics (set hard permanently, resist heat). Common properties are being light, waterproof, coloured and electrically insulating, which explain their wide use.

Choosing the right material

Choosing the right material brings it together: match a material's properties to the specification, then weigh cost, availability and environmental impact, and justify the final choice. This is the skill examiners test most often.

Choosing a material for an outdoor plant label

A plant label for a garden must be waterproof, must not rust, must take clear printed text, and must be cheap. Work through the material choice.

Step 1: List the properties the job needs

Waterproof and weatherproof for outdoor use, corrosion-free (no rust), able to take clear text, and low cost.

Step 2: Consider candidate materials

Mild steel (ferrous): cheap and strong, but rusts outdoors, so it fails the no-rust need unless coated. Aluminium (non-ferrous): does not rust, but dearer and harder to print on at school. Acrylic, a thermoplastic: waterproof, does not rust, takes printed or engraved text, and is cheap and easy to cut.

Step 3: Match each property to the candidate

Acrylic meets every point: it is waterproof and weatherproof, contains no iron so it cannot rust, takes clear text, and is low cost. Mild steel fails on rust; aluminium passes but costs more for no extra benefit here.

Step 4: State and justify the choice

Choose acrylic (a thermoplastic), because it is waterproof and rust-free for outdoor use, takes clear text, and is cheap and easy to cut, so it meets the specification at the lowest cost. The answer names the material, the property and the use, and weighs cost.

How this module is examined

Classify correctly. Hardwood vs softwood vs board; ferrous vs non-ferrous vs alloy; thermoplastic vs thermoset.
Link property to use. Name the property that makes a material suitable, then the use.
Justify selection. Match properties to the specification and weigh cost, availability and environment.
Avoid bare lists. A named material with no reason scores far less than a justified choice.

Check your knowledge

Short questions across the module. Attempt them, then check the worked solutions.

Name the three groups of wood and give one example of each. (3 marks)
State the difference between a ferrous and a non-ferrous metal, with one example of each. (2 marks)
State the simple test that distinguishes a thermoplastic from a thermosetting plastic. (1 mark)
State what you should match a material's properties to when selecting it. (1 mark)
A garden chair frame must be light, must not rust, and is left outdoors. Suggest a suitable material and justify it. (2 marks)

Sources & how we know this

Singapore-Cambridge GCE N(A)-Level Design and Technology (Syllabus 7055) — Singapore Examinations and Assessment Board (2026)